In the hills between Trebče and Zagaj, the River Bistrica has cut a 3-kilometre-long gorge, which is among the most picturesque and beautifully preserved river gorges in eastern Slovenia. The gorge is a natural monument, i.e. a geomorphological and hydrological natural heritage of national significance, which represents a superbly preserved example of the river ecosystem. The variety of the gorge is complemented by rich living nature. Here, we can find some lesser known and endangered plant species, such as the golden apple, Fringed Pink, hedgehog, rough horsetail, yellow whitlow-grass, yellow bellflower, butcher’s-broom, and yew. Interesting representatives of the animal kingdom include white-throated dippers, black stork, various species of butterflies and dragonflies, amphibians, vultures, and chamois, while trout and crayfish can be found in the water.
The gorge is accessible from the settlement of Zagaj, from where you can take a 2-kilometre-long walk on a footpath along the Bistrica river, whereby 400m of the gorge are not accessible on foot.
Beneath the village of Kunšperk, the River Sotla carved a 1.5km long dolomite gorge, which is now a protected natural monument as well as a geomorphologic, hydrologic, and an ecosystem natural value of national importance. The Sotla cuts through the land on the far eastern part of the Posavje hills in the transverse direction – the Kunšperk slope on the Slovenian side and the Cesarsko brdo hill on the Croatian side. Rock outliers rise from the steep forested slopes, karst caves can be found here, as well as a wide variety of flora and fauna. There are two castles at strategic positions – Kunšperk on the Slovenian side and Cesargrad on the Croatian side. The gorge is not easily accessible, therefore, the natural vegetation has mostly been preserved. The flora and fauna of the Zelenjak gorge is characterized by species mostly residing in beech forests of moderately high altitudes and rocky cliffs, however many species mostly found at the edge of forest and on forest clearings can also be found. More interesting animals living here are the chamois, bats (the Rhinolophus genus), birds of prey, owls, woodpeckers, some protected species of butterflies and beetles (e.g. the Jersey Tiger moth, southern festoon, stag beetle, beech carambycid and the Alpine longhorn beetle), and the otter in the River Sotla. Among plants, this selection could be even more extensive, however it is especially worth mentioning the rare narrow-leaved sandwort, Arctium lappa Asteraceae, Jovibarba hirta, highlander rose shades, some forest orchids, and numerous ferns (several species of spleenworts).
There is a forest path on the slope over the gorge leading to the Kunšperk castle and continuing to the Bizeljsko castle. You can also take a walk through the gorge on the road between the villages of Kunšperk and Orešje.
The Lurška jama cave, as the rock shelter is referred to by the locals, is carved into the Miocene sandstone (around 20 million years old). It is 40m wide and 17m high, and at some spots already covered in guhr. This is where the drinking water springs from, which is believed to have healing powers, especially when it comes to problems with the eyes. Pilgrims who went on a pilgrimage to the Church of Our Lady of Mercy in Zagorje also went through Lurška jama cave, because they believed that the water was very useful and had healing properties for the eyes. Approximately 100 years ago, an altar was built and religious ceremonies were held here, while nowadays this renovated rock-shelter hosts numerous cultural events. The Lurška jama cave is a point along the Mary’s pilgrimage route connecting places in Slovenia, Croatia and Austria.
Gruska, a natural monument as well as a geomorphological and hydrological natural heritage of national significance is a karst pocket valley that begins with a 30m high overhanging rock. The spring in the wall is generated by the water from the stream on the surface flowing from Kozje to Buče that disappears underground through a sinkhole. Gruska is an exemplary example of the karst water streaming system on a small surface, which is thus so much easier to showcase and explain especially to young people.
The Puščavnikova jama cave as well as the passage with the Gruska stream spring are caves in the literal sense of the word. The total length of the Puščavnikova jama cave is 22m and the altitude difference is 2 metres. It was named that way (Puščavnik – desert man) by the locals because a hermit used to live in the cave during and after World War I. The Gruska passage features an active water stream and is 26m long.
The valley, i.e. the bottom of the “cave”, features rich flora and fauna, encompassing crayfish, dragonflies (Odonata), caddisflies (Trichoptera), stoneflies (Plecoptera), bats (Chiroptera), as well as water mint (Mentha aquatica), water forget-me-not (Myosotis scorpioides), marsh horsetail (Equisetum palustre), and in the undergrowth the durable perennial honesty (Lunaria rediviva) and some species of hellebore.
The Gruska cave lies at the heart of the protected area of the Kozjansko Regional Park and represents one of the oldest documented and evaluated pieces of natural heritage inside the protected area.
The Gruska valley, which has lived in the consciousness of the locals through legends and stories for centuries, is one of the rare areas like this in eastern Slovenia. Through Gruska, you can follow a well-maintained trail with the descriptions of the flora and fauna.
‘Repnice’, holes dug into siliceous sand with unusual patterns that may let our imagination run wild, first appeared in regions surrounding Bizeljsko some 200 years ago. The holes were used for storing the harvest and fruit, while nowadays, these cavities are used as wine cellars. The village of Brezovica is the most famous settlements with regard to these unique wine cellars.
In the Župjek quartz sand extraction site, there is a nesting area of the colourful European bee-eater (Merops apiaster), which is a highly endangered species and thus also protected. It is endangered especially because the lack of suitable nesting walls. This very rare summer species is present in the area from the end of April until mid-August. It feeds on larger insects, which it catches in-flight: dragonflies, bumblebees, wasps, and bees. You can observe the European bee-eater nesting from the viewpoint under the nesting wall since the nesting walls must not be accessed during the nesting season (from the beginning of May until the end of July).
On a steep forested slope above the left bank of the Bistrica river under the village of Pilštanj, a picturesque rock, named the Ajdovska žena (Pagan Woman), was created in granular dolomite after the softer rock had been washed away. It is 12m high (7m on the gently sloping side) and 2m wide. The appearance of the rock is anthropomorphous. It resembles a woman who held a baby in her arms not long ago. The legend says that the Ajdi, mythological giants, used to live here and bring water from the Bistrica river. One very hot day, a pagan woman cursed the sun while carrying water from the Bistrica river up the steep slope while holding a baby in her arms. For cursing the sun, the source of life, the woman with the baby was punished by being turned to stone. Because of the natural processes, part of the rock, the baby, has fallen into the Bistrica gorge. The Ajdovska žena is nowadays a surface geomorphological natural monument.
If you go from the Kozje market towns past the Church of Our Lady of the Assumption, Krofln mill, and the abandoned lime kiln, you reach the narrow Bister graben valley, cut into the surface by a stream bearing the same name. Flora and fauna lovers will find much to see here. From here, you can ascend to the Kozje castle ruins, to Vilna peč – a rock shelter under the peak of Bredič, or up the Vetrnik slopes, where Žličar, the rock shepherd carving spoons in the steep slope, will welcome you.
Kozjansko park is an extremely rich environment with regard to the heritage of extraordinary trees – at least 12 venerable ancient trees 250 years of age or older. Rajgl bitter oak on Vetrnik, the linden tree in Bizeljska vas, Nujc oak in Gregovce, Žuraj oak in Križan vrh, hollies on Vetrnik, and the sycamore tree in Kozje are just a few of the examples. There are also numerous linden trees that are older than 200 years and with a trunk circumference at breast height exceeding 400cm, an extremely old and large service tree, one of the largest yew trees in Slovenia, huge chestnut trees, as well as exotic species, such as extraordinary pine trees, giant sequoias, honey locusts, cryptomeria, sycamore trees, as well as catalpas in the park next to Pišece castle.
Waterfalls, one of the most beautiful natural phenomena, are also quite frequent in the Kozjansko region. Kozjansko features numerous, prevailingly smaller hillside streams. Where the stream keeps flowing over harder and softer rock, thousands of years of erosion (removal of rock) created larger and smaller waterfalls. In many places, the calcium carbonate excretion on organic (plant and animal) waste has created Tufa thresholds and waterfalls.
Many waterfalls are hidden in gorges, however some can be spotted from your car. The most frequently visited are certainly the Bohor waterfalls since the “Trail of Four Waterfalls” passes by.
A special feature of the Kozjansko region is the solitary karst phenomenon, including sinkholes, dry valleys, springs, swallow holes, caves and abysses. This phenomenon can be found in areas of lithothamnion limestone, which used to be an important construction material since handymen used it to create portals, stones for manual presses and mills.